| Autor: |
Policht VR; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy., Russo M; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy., Liu F; Department of Chemistry, Stanford University, Stanford, California 94305, United States., Trovatello C; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy., Maiuri M; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy., Bai Y; Department of Chemistry, Columbia University, New York, New York 10027, United States., Zhu X; Department of Chemistry, Columbia University, New York, New York 10027, United States., Dal Conte S; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy., Cerullo G; IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy. |
| Abstrakt: |
Monolayer transition metal dichalcogenides (ML-TMDs) are two-dimensional semiconductors that stack to form heterostructures (HSs) with tailored electronic and optical properties. TMD/TMD-HSs like WS 2 /MoS 2 have type II band alignment and form long-lived (nanosecond) interlayer excitons following sub-100 fs interlayer charge transfer (ICT) from the photoexcited intralayer exciton. While many studies have demonstrated the ultrafast nature of ICT processes, we still lack a clear physical understanding of ICT due to the trade-off between temporal and frequency resolution in conventional transient absorption spectroscopy. Here, we perform two-dimensional electronic spectroscopy (2DES), a method with both high frequency and temporal resolution, on a large-area WS 2 /MoS 2 HS where we unambiguously time resolve both interlayer hole and electron transfer with 34 ± 14 and 69 ± 9 fs time constants, respectively. We simultaneously resolve additional optoelectronic processes including band gap renormalization and intralayer exciton coupling. This study demonstrates the advantages of 2DES in comprehensively resolving ultrafast processes in TMD-HS, including ICT. |
